Evolution of the DELLA gene family in plants and functional characterization of PmDELLA-like in the regulation of plant architecture in Prunus mume

DELLA proteins are central negative regulators of gibberellin (GA) signaling in plants; however, the evolutionary dynamics and functional roles of the DELLA gene family remain poorly understood. Here, we performed a comprehensive phylogenetic analysis of 807 DELLA proteins across 324 species and functionally characterized PmDELLA-like , a DELLA-like member in Prunus mume . Phylogenetic analysis revealed that DELLA proteins diverged into two monophyletic clades, DELLA I and DELLA-like, in seed plants, with lineage-specific expansion of DELLA I being a dominant trend in angiosperms. Ancestral sequence reconstruction uncovered a three-stage evolutionary pattern of the DELLA motif: a highly divergent pre-DELLA state in bryophytes, establishment of the conserved "DELLA" sequence in the common ancestor of vascular plants, and subsequent functional divergence into "DKELA/DELLA" (DELLA I) and "DGLLA" (DELLA-like) in seed plants. In P. mume , PmDELLA-like is highly expressed in shoot apical meristems and leaf primordia, and responds to GA treatment. Overexpression of PmDELLA-like in poplar resulted in a dwarf and multi-branched phenotype with shortened internodes, reduced endogenous GA content, and altered expression of genes involved in GA metabolism, circadian rhythm, and cell elongation. These findings suggest that PmDELLA-like modulates plant architecture by integrating GA signaling with light-responsive and cell elongation pathways, thereby playing a key role in coordinating growth and branching in woody plants. This study provides new insights into the evolution of the DELLA gene family and the regulatory mechanisms of plant architecture formation in woody plants, offering a theoretical basis for molecular breeding of ornamental tree species.